Preventing injury and death with lockout/tagout procedures
Among the risks facing people working with powered equipment is exposure to the uncontrolled release of hazardous energy during the installation, maintenance, service or repair of the equipment, which includes any machinery, processes and systems. According to the National Institute for Occupational Safety and Health, among the types of hazardous energy are electricity, mechanical motion, pressurized air and extreme temperatures.
Preventing workplace fatalities
From 1982 to 1997, NIOSH conducted a study of 1,281 fatal workplace accidents in 20 states as part of its Fatality Assessment and Control Evaluation program. It reports in the NIOSH Alert, Publication NO. 99-110 that 152 of these fatalities involved the installation, service, maintenance or repair on or near machines, equipment, processes or systems. Of the 152 fatalities reported, 82% were related to the failure to completely de-energize, isolate, block or dissipate the energy source. Another 11% were related to the failure to lockout and tagout energy control devices and isolation points after de-energizing, and the remaining 7% were related to the failure to verify that the energy source was de-energized before beginning work.
The NIOSH Alert reports that another study, conducted by the United Auto Workers of its members from 1973 to 1995 and released in 1997, attributed 20% of 414 workplace fatalities to inadequate hazardous energy control procedures, otherwise known as lockout/tagout. The report indicates that the energy sources involved in these fatalities included kinetic, potential, electrical and thermal energy. According to the report, kinetic, or mechanical, energy is generated in the moving parts of mechanical systems; potential energy is stored in pressure vessels, gas tanks, hydraulic and pneumatic systems and springs, and can be released as hazardous kinetic energy; electrical energy is generated from electrical power, static sources or electrical storage devices, such as batteries and capacitors; and thermal energy, of either high or low temperatures, results from mechanical work, radiation, chemical reactions or electrical resistance.
In response to risks posed by service and maintenance of plant equipment, the Occupational Safety and Health Administration of the U.S. Department of Labor introduced a standard for the Control of Hazardous Energy (Lockout/Tagout). Title 29 Code of Federal Regulations (CFR), Part 1910.147, issued in 1989, is a standard for practices and procedures for the disabling of machinery or equipment in order to prevent the release of hazardous energy while employees conduct installation, service, maintenance or repair. Lockout/tagout is required whenever workers are conducting operations that pose the risk of injury through either unexpected re-activation of the equipment or release of stored energy.
According to 29 CFR, Part 1910.147(b), a lockout is the “placement of a lockout device on an energy isolating device, in accordance with an established procedure, ensuring that the energy isolating device and the equipment being controlled cannot be operated until the lockout device is removed.” It further defines a lockout device as one “that utilizes a positive means such as a lock, either key or combination type, to hold an energy isolating device in the safe position and prevent the energizing of a machine or equipment.”
According to the same standard, a tagout is “the placement of a tagout device on an energy-isolating device, in accordance with an established procedure, to indicate that the energy-isolating device and the equipment being controlled may not be operated until the tagout device is removed.” It defines a tagout device as “(a) prominent warning device, such as a tag and a means of attachment, which can be securely fastened to an energy isolating device in accordance with an established procedure, to indicate that the energy isolating device and the equipment being controlled may not be operated until the tagout device is removed.”
Devices specifically designed for lockout/tagout use are available from a variety of manufacturers, including labels, tags, cards and signs. Locking devices are also available for ball and gate valves, cables, circuit breakers, plugs, switches, fuses and pneumatic equipment, as well as padlocks and hasps specifically designed for lockout/tagout procedures.
Lockout/Tagout, a fact sheet OSHA published in 2002, urges employers to establish standard procedures to protect workers from hazardous energy when they perform service or maintenance on plant equipment. These procedures should include the use of lockout and tagout devices and the de-energizing of machines and equipment during service and maintenance operations. The procedures should delineate each step in de-energizing equipment and applying lockout and tagout devices. Additionally, employers should provide training to ensure that affected employees understand the procedures and the importance of strictly observing them.
Employer standards must be tailored to the workplace and its equipment. The Lockout/Tagout fact sheet outlines what all standards require:
Development, implementation and enforcement of an energy control program
The use of lockout devices for equipment that can be locked out
Assurance that new or overhauled equipment can be locked out
Development, implementation and enforcement of a tagout program for equipment that cannot be locked out, which is as effective in protecting employees as a lockout program
Development, documentation, implementation and enforcement of energy control procedures
Use of only lockout and tagout devices authorized for particular equipment that are durable, standardized and substantial
Identification of individual users on all lockout and tagout devices
Establishment of policy that authorizes only the employee who applied lockout or tagout devices to remove them
Inspection of energy control procedures at least annually
Effective training for all employees affected by the standard
Compliance with additional energy control provisions in OSHA standards when equipment must be tested or repositioned, when outside contractors work at the site, in group lockouts and during shift and personnel changes.
The Lockout/Tagout fact sheet also encourages employers to consult OSHA for guidance in developing safety procedures and programs.
The NIOSH Alert explains that the de-energizing of equipment includes the disconnection or shutdown of engines or motors, the de-energizing of electrical circuits, blockage of fluid flow in hydraulic and pneumatic systems and blockage of machine parts against motion. It also indicates that in order to block dissipated stored energy, one must discharge capacitors, release or block springs under compression or tension and vent fluids from pressure vessels, tanks and accumulators. The NIOSH Alert urges the venting of toxic, flammable and explosive substances into the atmosphere, as well as the assurance that all sources of energy, including secondary power supplies, are isolated.
According to the NIOSH Alert, one must lockout or tagout all forms of hazardous energy, including electrical breaker panels and control valves. Once the equipment is disabled, mechanisms must be identified and labeled, as well as locked, according to the employer’s Energy Control Plan. Verification that the equipment has been de-energized includes ensuring that the main disconnect switch or circuit breaker cannot be moved to the on position. Again, only the employee who installed a lockout/tagout device may remove it.
Additionally, NIOSH recommends that lockout devices and keys be assigned to individual workers, in which each worker has only one key for his or her specific locking device. Lockout devices also should be clearly identified as such with tags that identify the employee or employees responsible for that device. In the event of a shift change, arriving workers should apply their locking devices prior to departing workers removing theirs. In the event of a worker’s absence, a set of master keys should be kept under supervisory control, to be used only under circumstances clearly delineated in the written Energy Control Plan.
Other suggestions that NIOSH makes include the identification and labeling of all hazardous energy sources, as well as the complete de-energizing, isolation, blockage or dissipation of all hazardous energy before beginning any work, which should be verified through testing or observation. Also inspect all work before reactivating equipment and ensure that the site is clear of all personnel before reactivation.
Fatalities occurring during the installation, service, maintenance and repair of machines, equipment, processes and systems can be prevented with the implementation and strict observance of a comprehensive procedure for controlling hazardous energy. It is essential that these procedures be written and distributed to all concerned employees, consistently enforced and reinforced with periodic, formal training. In addition to the mandatory compliance with OSHA regulations, maintaining a safe environment will prevent injury and death, as well as foster a more productive work environment.
Any person or organization with worker safety responsibility should conduct independent research to ensure full compliance with industry-specific or local laws and regulations.
Author Information Dan Vega is product manager for Thomas & Betts’ Industrial Products Group.
The Bottom Line…
Exposure to the uncontrolled release of hazardous energy during installation, maintenance, service or repair of equipment is among the risks facing people working with powered equipment.
Electricity, mechanical motion, pressurized air and extreme temperatures are among the types of hazardous energy that could be released.
Potential energy is stored in pressure vessels, gas tanks, hydraulic and pneumatic systems and springs, and can be released as hazardous kinetic energy.
Maintaining a safe working environment can prevent injury and death, as well as foster a more productive work environment.
Conduct independent research to ensure full compliance with industry-specific or local laws and regulations.
Wireless standards committee hears proposals
The SP100.11 and SP100.14 working groups of ISA’s SP100 committee for wireless industrial standards met to hear about a range of technology approaches that could help solve real-world wireless issues. The issues that the committee will focus on have been identified by user input and through use-cases collected by ISA.
The committee is working toward establishing standards, recommended practices, technical reports and related information that will define procedures for implementing wireless systems in the automation and control environment.
More than 20 companies from around the world presented their ideas and proposed solutions to the committee during the week. The committee will use the information that they’ve gathered from use cases and the information presented as a base for building an eventual standard.
“The number and variety of responses, with proposals coming from the United States, Canada, Japan, China, Germany and other countries, means that the standard will meet the needs of the global end-user community,” said SP100 co-chair Wayne Manges from the DOE’s Oak Ridge National Laboratory. “We will publish a standard that will stand the test of time by not only reflecting near-term solutions for wireless technology in industrial environments, but one that also allows for future technology advances and enhancements.”
As a basis for this effort, the committee has already reviewed more than 32 completed use cases and has more than 40 more that are underway, in various stages, from end-user companies. The use cases come from a variety of industries, including oil & gas, waste water treatment, nuclear power generation, food processing, chemicals manufacturing, aerospace and automotive.
“We’ve learned that most end user wireless site areas are quite large,” said Paul Sereiko, chairman of the marketing working group and president, KAPM Strategic Management. “The smallest we’ve seen is an automotive plant that covers several acres, and the largest is a wind farm that is 11 by 12 square miles.”
A number of technical presentations were given during the week-long meeting. Sessions included discussions on a number of existing radio protocol options such as IEEE’s 802.11 and 802.15.4; different ideas on how to address the various layers of the OSI reference model; and input covering several different security tactics. The input will be used by the committee to help decide the best approach or approaches to solving the critical end-user issues associated with the application of wireless technology in an industrial setting.
“We’ve learned that the data exchange rates (how often the user is measuring changes in the variable) cover three areas: the millisecond range; applications that need results in seconds; and where an application needs results in a minute or more. We also learned that the user expects the battery life of a wireless device to be about three to five years. These are powerful insights into what the users actually need from this standard,” said Greg LaFramboise of Chevron.